The pitfalls and promise of liquid biopsies for diagnosing and treating solid tumors in children : a review

Cell-free DNA profiling using patient blood is emerging as a non-invasive complementary technique for cancer genomic characterization. Since these liquid biopsies will soon be integrated into clinical trial protocols for pediatric cancer treatment, clinicians should be informed about potential applications and advantages but also weaknesses and potential pitfalls. Small retrospective studies comparing genetic alterations detected in liquid biopsies with tumor biopsies for pediatric solid tumor types are encouraging. Molecular detection of tumor markers in cell-free DNA could be used for earlier therapy response monitoring and residual disease detection as well as enabling detection of pathognomonic and therapeutically relevant genomic alterations. Conclusion: Existing analyses of liquid biopsies from children with solid tumors increasingly suggest a potential relevance for molecular diagnostics, prognostic assessment, and therapeutic decision-making. Gaps remain in the types of tumors studied and value of detection methods applied. Here we review the current stand of liquid biopsy studies for pediatric solid tumors with a dedicated focus on cell-free DNA analysis. There is legitimate hope that integrating fully validated liquid biopsy-based innovations into the standard of care will advance patient monitoring and personalized treatment of children battling solid cancers

A narrative review of 35 years of meta-[131I]iodobenzylguanidine therapy in neuroblastoma

Neuroblastoma is the most common extracranial solid malignancy of childhood. Approximately half of the patients have high-risk neuroblastoma (HR-NBL), typically presenting as widespread metastatic disease at diagnosis. Despite aggressive multimodality treatment, patients with HR-NBL have a long-term survival rate of below 50%. This is primarily due to frequent progression and relapse, which often proves to be therapy resistant. To overcome therapy resistance in HR-NBL, researchers are exploring diverse treatment strategies, including radionuclide therapy. Radiolabelled meta-iodobenzylguanidine (mIBG) has served as a theranostic (therapeutic and diagnostic) radiopharmaceutical in the field of neuroblastoma for several decades. [123I]mIBG scintigraphy is recognized as the international standard to evaluate disease dissemination at diagnosis and to monitor treatment response. In contrast, the role of [131I]mIBG therapy in the management of neuroblastoma is less clear. Over the past 35 years, [131I]mIBG therapy has been studied in more than 1500 patients with neuroblastoma. In initial studies, [131I]mIBG monotherapy was applied as a second-line treatment in patients who failed first-line treatment. In current applications, [131I]mIBG therapy is combined with chemotherapy, radiosensitizers, and/or immunotherapy, and is increasingly integrated in the first-line treatment of HR-NBL. This narrative review provides an overview of the literature on [131I]mIBG therapy in HR-NBL. Studies show that [131I]mIBG therapy can be an effective treatment in one-third of patients with acceptable toxicity. Further investigations, particularly randomized controlled trials, are needed to determine the efficacy and optimal use of [131I]mIBG therapy in HR-NBL

Refractory Stage M Ganglioneuroblastoma With Bone Metastases and a Favorable, Chronic Course of Disease:Description of a Patient Cohort

Refractory stage M neuroblastoma (NB) is associated with a poor prognosis and a progressive course of disease. Here, we describe a unique group of patients with a discrepant clinical course. Seven histologically confirmed ganglioneuroblastoma (GNB) (n=6) and differentiating NB (n=1) patients were identified who were diagnosed with stage M disease based on iodine-123-metaiodobenzylguanidine avid bone metastases. Six patients started on high-risk treatment, without tumor response (stable disease). Treatment was discontinued before the start of consolidation treatment because of refractory response in all patients. Unexpectedly, after cessation of treatment no progression of disease occurred. In 2 patients, the primary tumors expanded (>25%) very slowly during 1.5 and 3 years, and remained stable thereafter. Metabolically, a slow decrease of urinary homovanillic acid and vanillylmandelic acid levels and iodine-123-metaiodobenzylguanidine avidity was observed. All patients are alive with presence of metastatic disease after a median follow-up of 17 years (range: 6.7 to 27 y). Interestingly, at diagnosis, 6 patients were asymptomatic, 6 patients had GNB morphology, and 5 patients had meningeal metastases. These are all features seen in only a small minority of stage M patients. This GNB entity illustrates the clinical heterogeneity of neuroblastic tumors and can be used to further study the developmental origin of different NB subtypes

Thyroid function after diagnostic I-123-metaiodobenzylguanidine in children with neuroblastic tumors

BACKGROUND: Metaiodobenzylguanidine (MIBG) labeled with radioisotopes can be used for diagnostics 123I-) and treatment (131I-) in patients with neuroblastic tumors. Thyroid dysfunction has been reported in 52% of neuroblastoma (NBL) survivors after 131I-MIBG, despite thyroid protection. Diagnostic 123I-MIBG is not considered to be hazardous for thyroid function; however, this has never been investigated. Therefore, the aim of this study was to evaluate the prevalence of thyroid dysfunction in survivors of a neuroblastic tumor who received diagnostic 123I-MIBG only. METHODS: Thyroid function and uptake of 123I- in the thyroid gland after 123I-MIBG administrations were evaluated in 48 neuroblastic tumor survivors who had not been treated with 131I-MIBG. All patients had received thyroid prophylaxis consisting of potassium iodide or a combination of potassium iodide, thiamazole and thyroxine during exposure to 123I-MIBG. RESULTS: After a median follow-up of 6.6 years, thyroid function was normal in 46 of 48 survivors (95.8%). Two survivors [prevalence 4.2% (95% CI 1.2-14.0)] had mild thyroid dysfunction. In 29.2% of the patients and 11.1% of images 123I- uptake was visible in the thyroid. In 1 patient with thyroid dysfunction, weak uptake of 123I- was seen on 1 of 10 images. CONCLUSIONS: The prevalence of thyroid dysfunction does not seem to be increased in patients with neuroblastic tumors who received 123I-MIBG combined with thyroid protection. Randomized controlled trials are required to investigate whether administration of 123I-MIBG without thyroid protection is harmful to the thyroid gland

Pharmacological protection of the thyroid gland against radiation damage from radioactive iodine labeled compounds in children: a systematic review

Purpose: There is currently no consensus on which protective strategy is most effective to prevent I-131 uptake in the thyroid during medical interventions in children. We aimed to collect the best available evidence to determine which pharmacological intervention is most effective in protecting the thyroid gland from damage by radioactive iodine (RAI). Methods: Literature searches were performed using PubMed, Embase, OLDMEDLINE, and the Cochrane Central Register of Controlled Trials. Only original studies were included (1950–2022). Studies comparing pharmacological prevention of the thyroid against RAI uptake or occurrence of hypothyroidism, thyroid nodule or thyroid cancer were included. Included studies were graded according to the Grading of Recommendations Assessment, Development and Evaluation considerations. Pharmacological interventions were compared for effectiveness on reduction of thyroidal intake or relevant clinical thyroidal outcomes. Results: Forty studies were included. Quality of included studies was low and many different outcome variables were used, making meta-analysis impossible. In 81% of studies, the pharmacological intervention could not prevent RAI uptake or thyroid damage. The administration of potassium iodide (KI) 1 h before exposure to RAI seemed most effective to reduce thyroidal uptake, however, hypothyroidism was reported in up to 64% as well as several cases of thyroid carcinoma. The combination of KI, thyroxine and thiamazole reduced RAI uptake and occurrence of hypothyroidism; yet, after follow-up of 9 years, still 50% of patients developed hypothyroidism. KI with potassium perchlorate showed hypothyroidism to occur in up to 12% of patients after short follow-up time. Conclusions: The lack of well-designed studies impairs making strong recommendations on the optimal way to prevent thyroid damage when using radioactive coupled ligands for medical interventions. To improve the protection of the thyroid against radiation damage by I-131, well-designed randomized clinical trials with sufficient follow-up time, comparing new protective strategies’ effects on valid and well-defined thyroid outcomes are needed

Minimally invasive classification of pediatric solid tumors using reduced representation bisulfite sequencing of cell-free DNA : a proof-of-principle study

In the clinical management of pediatric solid tumors, histological examination of tumor tissue obtained by a biopsy remains the gold standard to establish a conclusive pathological diagnosis. The DNA methylation pattern of a tumor is known to correlate with the histopathological diagnosis across cancer types and is showing promise in the diagnostic workup of tumor samples. This methylation pattern can be detected in the cell-free DNA. Here, we provide proof-of-concept of histopathologic classification of pediatric tumors using cell-free reduced representation bisulfite sequencing (cf-RRBS) from retrospectively collected plasma and cerebrospinal fluid samples. We determined the correct tumor type in 49 out of 60 (81.6%) samples starting from minute amounts (less than 10 ng) of cell-free DNA. We demonstrate that the majority of misclassifications were associated with sample quality and not with the extent of disease. Our approach has the potential to help tackle some of the remaining diagnostic challenges in pediatric oncology in a cost-effective and minimally invasive manner. Translational relevance: Obtaining a correct diagnosis in pediatric oncology can be challenging in some tumor types, especially in renal tumors or central nervous system tumors. Furthermore, the diagnostic odyssey can result in anxiety and discomfort for these children. By applying a novel technique, reduced representation bisulfite sequencing on cell-free DNA (cf-RRBS), we show the feasibility of obtaining the histopathological diagnosis with a minimally invasive test on either plasma or cerebrospinal fluid. Furthermore, we were able to derive the copy number profile or tumor subtype from the same assay. Given that primary tumor material might be difficult to obtain, in particular in critically ill children or depending on the tumor location, and might be limited in terms of quantity or quality, our assay could become complementary to the classical tissue biopsy in difficult cases

Refractory Stage M Ganglioneuroblastoma With Bone Metastases and a Favorable, Chronic Course of Disease: Description of a Patient Cohort

Refractory stage M neuroblastoma (NB) is associated with a poor prognosis and a progressive course of disease. Here, we describe a unique group of patients with a discrepant clinical course. Seven histologically confirmed ganglioneuroblastoma (GNB) (n=6) and differentiating NB (n=1) patients were identified who were diagnosed with stage M disease based on iodine-123-metaiodobenzylguanidine avid bone metastases. Six patients started on high-risk treatment, without tumor response (stable disease). Treatment was discontinued before the start of consolidation treatment because of refractory response in all patients. Unexpectedly, after cessation of treatment no progression of disease occurred. In 2 patients, the primary tumors expanded (>25%) very slowly during 1.5 and 3 years, and remained stable thereafter. Metabolically, a slow decrease of urinary homovanillic acid and vanillylmandelic acid levels and iodine-123-metaiodobenzylguanidine avidity was observed. All patients are alive with presence of metastatic disease after a median follow-up of 17 years (range: 6.7 to 27 y). Interestingly, at diagnosis, 6 patients were asymptomatic, 6 patients had GNB morphology, and 5 patients had meningeal metastases. These are all features seen in only a small minority of stage M patients. This GNB entity illustrates the clinical heterogeneity of neuroblastic tumors and can be used to further study the developmental origin of different NB subtypes

Neuroblastoma stage 4S: Tumor regression rate and risk factors of progressive disease

Background: The clinical course of neuroblastoma stage 4S or MS is characterized by a high rate of spontaneous tumor regression and favorable outcome. However, the clinical course and rate of the regression are poorly understood. Methods: A retrospective cohort study was performed, including all patients with stage 4S neuroblastoma without MYCN amplification, from two Dutch centers between 1972 and 2012. We investigated the clinical characteristics, the biochemical activity reflected in urinary catecholamine excretion, and radiological imaging to describe the kinetics of tumor regression, therapy response and outcome. Results: The cohort of 31 patients reached a 10-year overall survival of 84% ± 7% (median follow-up 16 years; range, 3.3-39). During the regressive phase, liver size normalized in 91% of the patients and catecholamine excretion in 83%, both after a median of two months (liver size: range, 0-131; catecholamines: range, 0-158). The primary tumors completely regressed in 69% after 13 months (range, 6-73), and the liver architecture normaliz

Nuclear Medicine Imaging in Neuroblastoma: Current Status and New Developments

Neuroblastoma is the most common extracranial solid malignancy in children. At diagnosis, approximately 50% of patients present with metastatic disease. These patients are at high risk for refractory or recurrent disease, which conveys a very poor prognosis. During the past decades, nuclear medicine has been essential for the staging and response assessment of neuroblastoma. Currently, the standard nuclear imaging technique is meta-[123I]iodobenzylguanidine ([123I]mIBG) whole-body scintigraphy, usually combined with single-photon emission computed tomography with computed tomography (SPECT-CT). Nevertheless, 10% of neuroblastomas are mIBG non-avid and [123I]mIBG imaging has relatively low spatial resolution, resulting in limited sensitivity for smaller lesions. More accurate methods to assess full disease extent are needed in order to optimize treatment strategies. Advances in nuclear medicine have led to the introduction of radiotracers compatible for positron emission tomography (PET) imaging in neuroblastoma, such as [124I]mIBG, [18F]mFBG, [18F]FDG, [68Ga]Ga-DOTA peptides, [18F]F-DOPA, and [11C]mHED. PET has multiple advantages over SPECT, including a superior resolution and whole-body tomographic range. This article reviews the use, characteristics, diagnostic accuracy, advantages, and limitations of current and new tracers for nuclear medicine imaging in neuroblastoma

mRNA Expression Level of ALK in Neuroblastoma Is Associated with Histological Subtype, ALK Mutations and ALK Immunohistochemical Protein Expression

ALK is related to poor survival in neuroblastoma patients. We investigated the prognostic relevance of ALK mRNA expression and the relationship with ALK immunohistochemical expression, histological subtype and ALK aberrations. Whole transcriptome sequencing data were available from 54 patients. Overall survival (OS) and event-free survival (EFS) were estimated with Kaplan–Meier’s methodology. ALK protein expression was analyzed by immunohistochemistry. ALK aberrations were detected using whole exome sequencing, single nucleotide polymorphism array, next generation sequencing and/or fluorescence in situ hybridization. OS was 74.8% and EFS was 60%. ALK mRNA expression was not associated with OS (HR 1.127, 95% CI (0.812–1.854), p = 0.331) and adjusted EFS (HR 1.134, 95% CI (0.783–1.644), p = 0.505), but was associated with histological subtype (OR 1.914, 95% CI (1.083–3.382), p = 0.025) and ALK protein expression (negative versus weak: OR 2.829, 95% CI (1.290–6.204), p = 0.009) (negative versus moderate/strong: OR 2.934, 95% CI (0.889–9.679), p = 0.077). ALK mutated tumors had significantly higher ALK mRNA expression than non-mutated tumors (p < 0.001). MYCN-amplified neuroblastomas have higher MYCN mRNA expression (p ≤ 0.001), but not ALK mRNA expression (p = 0.553). ALK mRNA expression is higher in ALK mutated neuroblastomas and is associated with poorer differentiation degree and higher protein expression. ALK mRNA expression is not significantly associated with OS and EFS